(Sand voids, 40%; stone voids, 45%; Portland cement barrel yielding 3.65 cu. ft. of paste. Barrel specified to be 4.4 cu. ft.)
Proportions by Volume.1:2:41:2:51:2:61:2½:51:2½:61:3:4
Bbls. cement per cu. yd. concr't 1.30 1.16 1.00 1.07 0.96 1.08
Cu. yds. sand " " 0.42 0.38 0.33 0.44 0.40 0.53
Cu. yds. stone " " 0.84 0.95 1.00 0.88 0.95 0.71
Proportions by Volume.1:3:51:3:61:3:71:4:71:4:81:4:9
Bbls. cement per cu. yd. concr't 0.96 0.90 0.82 0.75 0.68 0.64
Cu. yds. sand " " 0.47 0.44 0.40 0.49 0.44 0.42
Cu. yds. stone " " 0.78 0.88 0.93 0.86 0.88 0.95

Note.—This table is to be used when the cement is measured loose, after dumping it into a box, for under such conditions a barrel of cement yields 4.4 cu. ft. of loose cement.

Thus for a 1:2:5 concrete, the sum of the parts is 1 + 2 + 5, which is 8; then 10 ÷ 8 is 1.25 bbls., which is approximately equal to the 1.30 bbls. given in the table. Neither is this rule nor are the tables applicable if a different size of cement barrel is specified, or if the voids in the sand or stone differ materially from 40 per cent. to 45 per cent. respectively. There are such innumerable combinations of varying voids, and varying sizes of barrel, that the authors do not deem it worth while to give other tables. The following amounts of cement per cubic yard of mortar were determined by test:

Authority Neat.1 to 11 to 21 to 31 to 41 to 51 to 61 to 71 to 8
Bbls. Bbls. Bbls. Bbls. Bbls. Bbls. Bbls. Bbls. Bbls.
Sabin 7.40 4.17 2.84 2.06 1.62 1.33 1.14 .... ....
W. B. Fuller 8.02 4.58 3.09 2.30 1.80 1.48 1.23 1.11 1.00
H. P. Boardman. 7.40 4.50 3.18 2.35 .... .... .... .... ....

The proportions were by barrels of cement to barrels of sand, and Sabin called a 380-lb. barrel 3.65 cu. ft., whereas Fuller called a 380-lb. barrel 3.80 cu. ft.; and Boardman called a 380-lb. barrel 3.5 cu. ft. Sabin used a sand having 38 per cent. voids; Fuller used a sand having 45 per cent. voids; and Boardman used a sand having 38 per cent. voids. It will be seen that the cement used by Sabin yielded 3.65 cu. ft. of cement paste per bbl. (i. e. 27 ÷ 7.4), whereas the (Atlas) cement used by Fuller yielded 3.4 cu. ft. of cement paste per bbl. Sabin found that a barrel of cement measured 4.37 cu. ft. when dumped and measured loose. Mr. Boardman states a barrel (380 lbs., net) of Lehigh Portland cement yields 3.65 cu. ft. of cement paste; and that a barrel (265 lbs., net) of Louisville natural cement yields 3.0 cu. ft. of cement paste.

Mr. J. J. R. Croes, M. Am. Soc. C. E., states that 1 bbl. of Rosendale cement and 2 bbl. of sand (8 cu. ft.) make 9.7 cu. ft. of mortar, the extreme variations from this average being 7 per cent.

Frequently concrete is made by mixing one volume of cement with a given number of volumes of pit gravel; no sand being used other than the sand that is found naturally mixed with the gravel. In such cases the cement rarely increases the bulk of the gravel, hence Table XIV will give the approximate amount of cement, assuming 1 cu. yd. of gravel per cubic yard of concrete.

Table XIV.—Showing Barrels of Cement per Cubic Yard of Various Mixtures of Cement and Pit Gravel.

Spc. Vol. of bbl. cu. ft.Barrels of Cement per Cubic Yard of Concrete for Mixtures of
1-5 1-6 1-7 1-8 1-9 1-10 1-12
3.8 1.41 1.18 1.01 0.874 0.789 0.71 0.59
4.4 1.25 1.02 0.875 0.766 0.681 0.61 0.51